package com.soft.mainsite.common.utils;

import com.soft.mainsite.common.constant.NumericConst;

import javax.crypto.*;
import javax.crypto.spec.SecretKeySpec;
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

/**
 * EncryptUtil
 *
 * @author jin
 * @date 2017/05/09
 */
public class EncryptUtil {

    public static String encryptByHex(String str1, String salt) {
        String salts = CheckSumUtil.getMD5(salt);
        return parseByte2HexStr(encrypt(str1, salts));

    }

    public static String decryptToString(String st1, String salt) {
        String salts = CheckSumUtil.getMD5(salt);
        byte[] decryptFrom = parseHexStr2Byte(st1);
        byte[] decryptResult = decrypt(decryptFrom, salts);
        return new String(decryptResult);

    }

    /**
     * 加密
     * <p>
     * 需要加密的内容
     *
     * @param str
     * @return
     */
    public static byte[] encrypt(String str, String salt) {
        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(salt.getBytes()));
            SecretKey secretKey = kgen.generateKey();
            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            // 创建密码器
            Cipher cipher = Cipher.getInstance("AES");
            byte[] byteContent = str.getBytes("utf-8");
            // 初始化
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byte[] result = cipher.doFinal(byteContent);
            // 加密
            return result;
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 解密
     * <p>
     * 待解密内容
     *
     * @param str 解密密钥
     * @return
     */
    public static byte[] decrypt(byte[] str, String salt) {
        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(salt.getBytes()));
            SecretKey secretKey = kgen.generateKey();
            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            // 创建密码器
            Cipher cipher = Cipher.getInstance("AES");
            // 初始化
            cipher.init(Cipher.DECRYPT_MODE, key);
            byte[] result = cipher.doFinal(str);
            // 加密
            return result;
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 将二进制转换成16进制
     *
     * @param buf
     * @return
     */
    public static String parseByte2HexStr(byte[] buf) {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < buf.length; i++) {
            String hex = Integer.toHexString(buf[i] & 0xFF);
            if (hex.length() == 1) {
                hex = '0' + hex;
            }
            sb.append(hex.toUpperCase());
        }
        return sb.toString();
    }

    /**
     * 将16进制转换为二进制
     *
     * @param hexStr
     * @return
     */
    public static byte[] parseHexStr2Byte(String hexStr) {
        if (hexStr.length() < 1) {
            return null;
        }
        byte[] result = new byte[hexStr.length() / 2];
        for (int i = 0; i < hexStr.length() / NumericConst.NUMBER_TWO; i++) {
            int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
            int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2), 16);
            result[i] = (byte) (high * 16 + low);
        }
        return result;
    }
}
